Lubricating oil additives



United States Patent Ofiiice Weiterstadt, and Nicolaus Jochum, Darrnstadt, Germany, assignors to Rohm & Haas G.m.b.H., Darinstadt, Germany No Drawing. Filed Aug. 8, 1960, Ser. No. 47,919 Claims priority, application Germany, Aug. 12, 1959,

4 Claims. clan-51.5

This invention relates to lubricating oil additives, to compositions containing such additives, and to methods of making such additives and Compositions.

It is known in the art that copolymers containing acrylic acid esters or methacrylic'acid esters of a long chain alcohol can be employed as lubricating oil additives. To be sure, these products have a beneficial influence on the viscosity-temperature relationship. However, their use requires an increase, over the amounts normally used in lubricating oils, of dispersing agents therewith. i

Another problem is the formation of so-called cold sludge. This sludge is formed in combustion engines operating underminirnal loads using common fuels be cause of contamination of the lubricating oil by water, incompletely combusted products of the fuel, and oxidation products of the lubricating oil. The sludge separates in cold weather.

The addition ofvcopolymers of methacrylic acid esters art additives are avoidedby the use as lubricant additives of copolymers comprising: (1') 3-60 percent by. weight (preferably 15 -40v percent) of unsaturated carboxylic acid esters of lower alkanol amides or saturated fatty acids, the fatty acid portion of which contains 1-20 carbonatoms; and (2) 97+40-weight percent of esters of acrylic and/ or methacrylic acid having 822 carbon atoms in the alcohol moiety thereoli; f

Suitableesters of 'polymerizable carboxylic .acids and fatty acid alkariol amides can be exemplified by the esters of acrylic or methacrylicacid with coconut'oil acid monoethanol amide, coconut oil acid-N-methylethanolamide, acetic acid monoethanolamide, v propionic acid monoethanolamide, andthe like. The esters of dimeric methacrylic acidwith the ethanol amides mentioned' can alsobe used. j 5 The. inclusion of other monomers in the copolymers,

, 3,163,605 Patented Dec. 29, 1964 a simultaneous bettering of the temperature-viscosity relationship and the pour point of the mineral or synthetic oils is obtained. Synthetic oils such as the esters of branched chain C C aliphatic alcohols with aliphatic dicarboxylic acids or, for example as are described in copending applications Ser. Nos. 734,449, now abandoned, 773,195, now Patent No. 3,058,913, 5,663, now abandoned, and 9,421, now abandoned, can be improved by the additives taught herein. 7 V

The copolymeric additives are prepared, for example, by solution polymerization with the exclusion of oxygen, and can be prepared with the joint use of polymerization modifiers. When the copolymers are prepared in solution, the lubricating oil to be improved can conveniently serve as a solvent. Conventional techniques, old in the art for addition polymerization, are employed, such as irradiation with ultraviolet light, the use of catalytic redox systems such as per-compounds in combination with reducing substancessuch as tertiary amines like p-chlorotoluidine, by simple heating, or by heating to 25-110 C. in the presence of a free-radical generating catalyst such as the azo compounds (e.g., azodiisobutyronitrile, etc.) or peroxides or hydroperoxides (e.g., benzoyl peroxide, lauryl peroxide, 2,4-dichlorobenzoyl peroxide, di-tbutyl peroxide, t-butyl hydroperoxide, cumene hydroperoxide, t-butyl perbenzoate, etc.). From the intrinsic viscosities of the polymer products, it is believed that they have molecular weights ranging between 20,000 and 25,000.

A better understanding of the invention and of its many advantages can be had by reference to the following specific examples given by way of illustration.

EXAMPLE 1 A mixture of about grams of lauryl methacrylate, 20 grams .of coconut oil acid monoethanol amide methacrylate, 20 grams of methylmethacrylate, and 0.4 gram of azodiisobutyrodinitrile were dissolved to form a 40 percent solutionin a mineral oil having the following characteristics? Visci' R centistokes 17.0 ViSC210= "F .d 0 Viscosity index (V.I.) -Q 92 D 00. 0.862 Pour point C -28 The materials were polymerized by heating at C. with exclusion of atmospheric oxygen. After 6 hours,

' the polymerization was completed. -:The materials which in particularlower alkyl esters'of acrylic and methacrylic I acids, is'useful in certain cases. ,The amount'of such monomers, added is chosen such that the oil solubility of the copolymers formed is retained, and is generallybetween about '1020 percent by weight'of the copolymer..

Still other nitrogen containing comonomers, particu-" larly acrylic and/or methacrylic acid lower alkyl amides and their substitution products,"acrylonitrile, or unsaturated heterocyclic compounds such as vinyl pyrrolidones amounts up-to l5 percentlby weight. V The copolyrners are suitably added to'jminer'al or'synthetic ester oils in amounts offrorn 1 toll) percent. In

can advantageously beiricluded vin the copolymers in this manner, an'outs tanding dispersing ettect as well ashad not reactedkwere distilled off at a temperature of 170 C. under 1 mm. Hg pressure. Thepolymer solution remaining was a clear and viscous product which contained 0.3-0.4 percent of nitrogenj The'properties of a 4 percentfmineral oil solution of the 40 percent polymer concentrate prepared above are given in the following Table I. I a Table l V l i V 6 F 7l.0 centistokes. V r 0.40 centistokes. 1 V.I.- (viscosity index) 129; I Pour point lowering .10-l2' C. Stripe test Blank stripe.

Motortest 50 hrs./ 10 f C. (lcylinder V diesel motor of the Motorenwerke.

Mannheim Type KD 12 E) 91 points.

Details of the methods used to determine properties mentioned in the examples are as follows. The viscosity measurements were made with 4 percent solutions of the sample (about 40 percent) in mineral oil (V -=50.9 cst.; V 0 =6.95 cst.; V.I.=l01). Pour points were determined on 0.1 percent solutions in regenerated motor oil pour point 16 C.). The stripe test was according to the method of L. G. Wood and M. Buchwald (Ind. Eng. Chem. 48, 1925-30, 1956) using a 3 percent solution in mineral oil SAE 20W20 with the addition of 0.4 percent zinc-alkyl-dithiophosphate. The asphalt test (a determination of dispersion efficacy) was performed according to the method of C. J. Prizer (Petroleum 21, November 1958, No. 11, page 395), using 1.5 percent solutions of the 40 percent preparation in mineral oil. The motor test employed is described in Erdol und Kohle 6, 484 et seq. (1959).

EXAMPLE 2 A copolymer of 73 grams lauryl methacrylate, 15 grams methyl methacrylate, and 12 grams of propionic acid monoethanol amide methacrylate was prepared according to the method of Example 1.

EXAMPLE 3 According to the process of Example 1, a copolymer of 75.5 grams of tetradecyl methacrylate, 11.0 grams of coconut oil acid monoethanol amide methacrylate, grams of methyl methacrylate, and 3.5 grams of N-isobutyl-methacrylamide was prepared.

The properties of a 4 percent solution in mineral oil of the 40 percent concentrate prepared above are given in the following Table II.

EXAMPLE 4 The dimerization product of methacrylic acid methyl ester, prepared according to German Patent 855,554 or 903,932, was submitted to alcoholysis with coconut oil acid monoethanol amide. 10 grams of the reaction product, 72.5 grams of hexadecyl methacrylate, and 17.5 grams of methyl methacrylate were copolymerized according to the method of Example 1. a 7

EXAMPLE '5 A mixture of 62.5 grams lauryl methacrylate, 27.5 grams coconut oil acid-N-methylethanolamide-methacrylate, and 10 grams methyl methacrylate were prepared according to the process of Example 1.

EXAMPLE 6 j 52 grams of mixed acrylic esters of coconut oil alcohols having 12-18 carbon atoms (average chain length 'C 28 grams of coconut oil fatty acid monoethanol amide methacrylate, and grams of butyl acrylate were copolymerized in mineral oil to give a 40 percent solution of the polymer. The resulting solution was-added to mineral oils to incorporate the additive thereinto in amounts of from 1-10 percent by weight.

EXAMPLE 7 An additive was formed, in mineral oil suificient to give a 40 percent solution, by copolymerization of 77 grams of coconut oil methacrylates (chain length of alcohol moiety C C average chain length C 13 grams of acetic acid-N-methyl monoethanolamide methacrylate, and 10 grams of isobutyl methacrylate.

EXAMPLE 8 Especially advantageous copolymeric additives containing nitrogenous comonomers were prepared by copolymerizing 62 grams of coconut oil alcohol methacrylic acid esters (as described in previous examples) with 28 grams of coconut oil fatty acid monoethanolamide methacrylate, and 10 grams of N-dimethylaminoethylmethacrylate in sufficient mineral oil to yield a percent solution.

"EXAMPLE 9 A particularly good additive was prepared by copolymerization of 77 grams of coconut oil alcohol methacrylic acid esters as described earlier, 10 grams of butyl acrylate, 8.5 grams of coconut oil fatty acid N-methyl-monoethanolamide methacrylate, and 4.5 grams of N-vinyl-Z- pyrrolidone in suificient mineral oil to give a 40 percent solution.

The additives according to the invention have the great advantage over known nitrogen-containing lubricant additives that their use prevents formation of sludge in a motor, and the consequences of sludge formation, such as corrosion, are avoided. A lubricating oil which, for example, contains a copolymer of methacrylic acid dodecyl ester and methacrylic acid amide in a proportion of 6:1 dissolved therein under comparable conditions forms a highly viscous slimy oil in the test motor. Further, the products according to the invention show an advantageous influence on the VJ. value and the pour point of the oil. They can also be used in combination with known lubricating oil additives and dispersing agents. German specification 1,058,672 describes lubricating oil additives which are copolymers formed in part from amides or amide salts of alpha,beta-unsaturated carboxylic acids, wherein the nitrogen atom of the amide or amine salt can also be obund to a hydrocarbon radical substituted with an amino group. As compounds of this type, for example, are diethyltriarnine salts of acrylic or methacrylic acid, or N-(2-aminoethyl)-methacrylic acid amide. In the corresponding British Patent 759,918, copolymers of esters of alpha,beta-unsaturated carboxylic acids with amino-alcohols are additionally taught as lubricating additives.

These materials are distinguished by their structure from those of the present invention and are inferior technically to them, as will be evident from the following comparative tests.

The reaction product (ProductA) of a dodecyl methacrylate-maleic acid anhydride-copolymer with ethanolamine, prepared according to Example 6 of German specification 1,058,672, was compared in its sludge-inhibiting effects with the material prepared according to Example 5 of the present specification (Product B). A cold-sludge test was carried out by introducing the combustion products of a gasoline flame into the oil to be treated, which oil contained 3 'weight percent of a 40 percent solution of the test additive in SAE 20W/20 motor oil, at 40-50? C. For Product A, precipitation took place even after 30 minutes, whereas Product B first showed a slight formationof precipitate after 4 /2 hours.

German Patent. 1,045,658 teaches the use as lubricant additives of the products obtained by alkaline hydrolysis .or alcoholysis in the presence of ammonia or amines at 5 Table III Product accord- Product according to example 1 ing to example 4 of the present otGerman patent invention 1,045,658

Viscosity of a 4 solution in Miner Oil:

At 100 F 71.00 est 72.60 cst At 210 F 10.40 est 10.55 est VI- 129 129. Pour point lowering 1012 (J 10-12 C. Stripe Test Blank stripe. Stripe half covered with deposit. Asphalt Test No precipitate. Slight precipi- Motor Test 50 hrs/100 C. (1 91 points 87 points.

cylinder diesel motor of the Motorenwcrke Mannheim Type KD 12 E).

Although specific embodiments have been shown and described, it is to be understood that they are illustrative, and are not to be construed as limiting on the scope and spirit of the invention.-

What is claimed is:

1. A lubricating composition consisting essentially of a major proportion of lubricating oil selected from the group consisting of mineral oils and synthetic ester oils, and from 1 to 10 percent by weight of an oil soluble, at least ternary copolymer of (1) 3 to 40 percent by weight of an ester formed between an alkanolarnide of a fatty acid having 1 to 20 carbon atoms and a member selected from the group consisting of acrylic acid and methacrylic acid, (2) at least one member selected from the group consisting of (A) 10 to 20 percent by weight of an ester formed between a lower alkanol having up to 4 carbon atoms and a member selected from the group consisting of acrylic acid and methacrylic acid, and (B) up to 15 percent by Weight of a nitrogenous monomer selected from the group consisting of amides of acrylic and methacrylic acid with a lower alkyl amine having up to 4 carbon atoms, acrylonitrile, and N-vinyl pyrrolidone, the balance of said at least ternary copolymer, comprising at least 40 percent by weight of said copolymer, being (3) an ester formed between an alcohol having 8 to 22 carbon atoms and a member selected from the group consisting of acrylic acid and methacrylic acid.

2. A lubricating composition as in claim 1 wherein said copolymer is a ternary copolymer between components (1), (2) (A), and (3), as defined in claim 1.

3. A lubricating composition as in claim 1 wherein said copolymer is a ternary copolymer between components (1), (2) (B), and (3), as defined in claim 1.

4. A lubricating composition as in claim 1 wherein said copolymer is a quaternary copolymer formed between components (1), (2) (A), (2) (B), and (3), as defined in claim 1.

References Cited in the file of this patent UNITED STATES PATENTS 2,718,515 Thomas Sept. 20, 1955 2,737,496 Catlin Mar. 6, 1956 2,806,018 Price Sept. 10, 1957 2,830,954 Dixon Apr. 15, 1958 2,892,816 Lowe et a1 June 30, 1959 12,912,416 Newey Nov. 10, 1959 2,944,974 Lorensen et a1 July 12, 1960 3,030,303 Ryan Apr. 17, 1962 FOREIGN PATENTS 266,954 Australia Feb. 23, 1960 1,058,672 Germany June 4, 1959 759,918 Great Britain Oct. 24, 1956 

1. A LUBRICATING COMPOSITION CONSISTING ESSENTIALLY OF A MAJOR PROPORTION OF LUBRICATING OIL SELECTED FROM THE GROUP CONSISTING OF MINERAL OILS AND SYNTHETIC ESTER OILS, AND FROM 1 TO 10 PERCENT BY WEIGHT OF AN OIL SOLUBLE, AT LEAST TERNARY COPOLYMER OF (1) 3 TO 40 PERCENT BY WEIGHT OF AN ESTER FORMED BETWEEN AN ALKANOLAMIDE OF A FATTY ACID HAVING 1 TO 20 CARBON ATOMS AND A MEMBER SELECTED FROM THE GROUP CONSISTING OF ACRYLIC ACID AND METHACRYLIC ACID, (2) AT LEAST ONE MEMBER SELECTED FRM THE GROUP CONSISTING OF (A) 10 TO 20 PERCENT BY WEIGHT OF AN ESTER FORMED BETWEEN A LOWER ALKANOL HAVING UP TO 4 CARBON ATOMS AND A MEMBER SELECTED FROM THE GROUP CONSISTING OF ACRYLIC ACID AND METHACRYLIC ACID, AND (B) UP TO 15 PERCENT BY WEIGHT OF A NITROGENOUS MONOMER SELECTED FROM THE GROUP CONSISTING OF AMIDES OF ACRYLIC AND METHACRYLIC ACID WITH A LOWER ALKYL AMINE HAVING UP TO 4 CARBON ATOMS, ACRYLONITRILE, AND N-VINYL PYRROLIDONE, THE BALANCE OF SAID AT LEAST TERNARY COPOLYMER, COMPRISING AT LEAST 40 PERCENT BY WEIGHT OF SAID COPOLYMER, BEING (3) AN ESTER FORMED BETWEEN AN ALCOHOL HAVING 8 TO 22 CARBON ATOMS AND A MEMBER SELECTED FROM THE GROUP CONSISTING OF ACRYLIC ACID AND METHACRYLIIC ACID. 